IGF 1 LR3 in Aesthetic and Anti Aging Medicine: Benefits and Risks Hubmed What is IGF 1 LR3?, Insulin Like Growth Factor 1 Long R3 (IGF 1 LR3) is a modified version of IGF 1 with a longer half life, making it significantly more potent and effective for muscle growth, IGF 1 LR3 active protein P05019.1 MyBioSource Attenuated glucose stimulated insulin secretion during an acute IGF 1 LR3 infusion into fetal sheep does not persist in isolated islets Journal of Developmental Origins of Health and Disease Cambridge Core